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TOPIC 24

ORGANISMS AND THEIR ENVIRONMENT

CEB Textbook Chapter 18, pages 373-379

Mastering Biology, Chapter 18

LEARNING OBJECTIVES

Define the following terms: ecology, abiotic component of the environment, biotic component of the environment and biosphere

List and describe the four levels of ecology: organismal, population, community and ecosystem.

List and describe the major abiotic factors affecting the distribution of life in the biosphere.

Define and describe examples of the three main types of adaptations that enable plants and animals to adjust to changes in their environments.

FIGURE 18.0

What is Ecology??

WHAT IS ECOLOGY?

Ecology has four levels...

Organismal Ecology - Adaptations

Population Ecology – Population density and growth

Community Ecology – Interactions between species, structure and organization of community

Ecosystem Ecology – Energy flow and the cycling of chemicals in ecosystems

Ecology is the scientific study of the interactions

between organisms and their environments.

Organismal

Population Community

Ecosystem

BIOSPHERE

Patterns in the distribution of life mainly reflect

differences in the abiotic factors of the

environment.

The biosphere is

the global ecosystem,

the sum of all the

planet’s ecosystems,

or

all of life and where it

lives.

ECOSYSTEMS

An ecosystem consists of all the living organisms in a

given area, along with the abiotic factors that influence

them.

Ecosystems are dynamic,

continually changing as the

organisms within them interact

with one another, and the ever

changing environment.

Energy and nutrients generally

flow between organisms within

the same ecosystem, and little

is lost to the outside.

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BIOTIC AND ABIOTIC FACTORS

An ecosystem is formed of biotic and abiotic components.

Biological organisms are part

of their ecosystem’s biotic

component. The organisms

within an ecosystem all affect

one another, acting as either

an energy source, or a

competitor.

Some abiotic factors, such as the soil, can be altered by the

presence of organisms.

The abiotic component is the non-biological part of an

ecosystem. This includes the climate, light level and

rainfall.

ACTIVITY: ABIOTIC AND BIOTIC FACTORS

IMPORTANT ABIOTIC FACTORS OF THE

BIOSPHERE Energy source – most ecosystems powered by sunlight

which provides energy for photosynthesis and primary production

Temperature – affects metabolism, few organisms can function below 0ºC, enzymes of most organisms are destroyed above 45ºC

Water – is essential to all life. Terrestrial organisms need to prevent drying out and aquatic organisms need to balance their solute concentration

Inorganic Nutrients – The distribution of photosynthetic organisms (plants, algae, bacteria) is usually limited by availability of nitrogen and phosphorus.

Aquatic organisms are more affected by factors like salinity, dissolved oxygen, currents and tides

Terrestrial organisms are more affected by winds, storms, fire etc.

FIGURE 18.6

Hydrothermal Vent: Energy Source hydrogen sulfide (Chemoautotrophic bacteria)

FIGURE 18.7

Endotherm – ‘warm blooded’

FIGURE 18.8

(a) Scales on a basilisk lizard

(b) Beaded water droplets

Adaptations to drying out

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FIGURE 5.14

Animal cell

Plant cell

Normal

Flaccid (wilts)

Lysing

Turgid (normal)

Shriveled

Shriveled

Plasma

membrane

H2O H2O H2O H2O

H2O H2O H2O H2O

(a) Isotonic

solution

(b) Hypotonic

solution (c) Hypertonic

solution

Aquatic organisms need to adapt to salinity of water

BIOMES

A biome is

a major terrestrial or aquatic

life zone,

characterized by

vegetation type in

terrestrial biomes or

the physical environment

in aquatic biomes.

• Freshwater Biomes – cover less

than 1% of Earth, contain .01% of

its water, 6% of its species, used for

all our drinking water!!

•Marine Biomes – cover over 70%

of Earth!

Terrestrial Biomes

FIGURE 18.27

Temperate broadleaf forest

Coniferous forest

Arctic tundra

High mountains (coniferous forest and

alpine tundra)

Polar ice

Tropical forest

Temperate grassland

Chaparral

Desert

Savanna

Key

Tropic of Capricorn

30º N

Equator

30º S

Tropic of

Cancer

THE EVOLUTIONARY ADAPTATIONS OF

ORGANISMS

The ability of organisms to

live in Earth’s diverse

environments demonstrates

the close relationship

between the fields of

- ecology and

- evolutionary biology.

Evolutionary adaptation via

natural selection results

from the interactions

between

- organisms and their

- environments.

(selective pressure)

An adaptation, also

called an adaptive trait,

in biology is a trait with

a current functional role

in the life history of an

organism that is

maintained and evolved

by means of natural

selection.

ADJUSTING TO ENVIRONMENTAL CHANGE

Behavioural response – migrates to warmer regions

Anatomical/structural response – grows heavier feathers

Physiological response – fluffing feathers to trap more heat

Birds may adapt to cold by...

These responses, which

occur during the lifetime of

an individual, do not qualify

as evolution, which is

change in a population

over time.

PHYSIOLOGICAL RESPONSES

Acclimation is

gradual,

reversible, and

a physiological

adjustment to an

environmental change.

Physiology - the

chemical or physical

functions that exist

in a living system

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ANATOMICAL RESPONSES

Change in body shape or structure

An example of an anatomical

acclimatisation would be a heavier fur coat

in response to the cold

FIGURE 18.12

BEHAVIOURAL RESPONSES

In contrast to plants, most animals can respond to an unfavourable change in the environment by moving to a new location

Ectotherms may shuttle between sun and shade

Migratory birds travel great distances in response to changing seasons

Humans have an especially rich range of behavioural responses

ACTIVITY: TYPES OF ADAPTATIONS

NICHES

All organisms occupy a specific niche within an ecosystem.

A niche is often described as an organism’s role within its

ecosystem. It encompasses its food source, habitat,

physiology and behaviour.

Natural selection ensures that organisms are adapted to a

specific niche.

Overlap between the niches of two species in the same

ecosystem results in interspecific competition.

How are these

two finches

adapted for

different niches?

HOW DO ALL THESE WORDS RELATE?

Population

Habitat

Abiotic

Biotic

Community

Niche

Ecosystem

Biomes

Biosphere

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Habitat – An organism’s habitat

is the specific environment it lives in and

includes the biotic and abiotic factors of its surroundings.

where Shrek lives (swamp)

Population – All of the individuals of the

same species in a given area

Community – All the populations of

living organisms in an ecosystem

The absence

of sunlight is

an abiotic

factor which

influences

princess

fiona in her

environment

Magic mirror is an abiotic factor, it is non-

living but has an influence on organisms in

their environment.

Biotic factor: Prince charming and shrek are

competitors, trying to fill the same niche

(being the husband of Fiona)

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Food chain or predation

Abiotic

factors

A community of different species of animals and plants

Energy flow

through

food chains

& webs Cycling

of

nutrients

Ecosystem - consists of all the living organisms in a given

area, along with the abiotic factors that influence them.

Community. (Biomes:

Madagascar is mostly

deciduous forest, with tropical

forest also)

Word

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HOMEWORK

Learn the 5 important abiotic factors affecting

organisms

DO NOW match Ecology Words to their

meanings. At home, cut out meanings and

glue in correct positions.